Compressor cycling unit

ABSTRACT

My invention provides a compressor cycling control unit between the high pressure side of the compressor and the low pressure or suction side thereof. This unit cycles the compressor &#39;&#39;&#39;&#39;on and off&#39;&#39;&#39;&#39; between compressing and non-compressing. With my improved control it is possible to keep the compressor running whenever the driving engine is running, even though a magnetic clutch may be employed to stop and start the compressor in the conventional manner since it is controlled by the same cycling unit. With the combination expansion valve and holding valve, the system is maintained under constant pressure so that it is immediately operable.

United States Patent 1 Niekell 51 Dec. 30, 1975 Primary Examiner-William E. Wayner [57] ABSTRACT My invention provides a compressor cycling control unit between the high pressure side of the compressor and the low pressure or suction side thereof. This unit cycles the compressor on and of between compressing and non-compressing. With my improved control it is possible to keep the compressor running whenever the driving engine is running, even though a magnetic clutch may be employed to stop and start the compressor in the conventional manner since it is controlled by the same cycling unit.

With the combination expansion valve and holding valve, the system is maintained under constant pressure so that it is immediately operable.

5 Claims, 7 Drawing Figures 3s 40 2 32 g 1 a 3'8 U.S. Patent Dec.30, 1975 Sheet 1 of4 3,928,984

atant Dec. 30, 1975 Sheet 3 of4 3,928,984

US. Patent Dec. 30, 1975 Sheet 4 of 4 COMPRESSOR CYCLING unlr RESUME OF THE PRIOR ART In the conventional system used in automotive vehicles a magnetic clutch is employed to start and stop the compressor. This is achieved through a combination of I a high pressure low pressure switch or a minimum temperature switch. The minimum temperature switch keeps the compressor running all of the time while the control panel is turned on and the compressor then operates at maximum output. This is wasteful of energy and wears out the compressor.

These difficulties can be overcome by the use of a cycling control unit interposed in the low pressure circuit between the evaporator and the compressor, and in the high pressure circuit between the compressor and the condenser.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an automotive air conditioning system embodying my invention.

FIG. 2 is an end elevation of the cycling control unit thereof.

FIG. 3 is a longitudinal sectional view taken substantially on the line 3-3 of FIG. 2 looking in the direction of the arrows.

FIG. 4 is a side elevational view of the Cycling control unit.

FIG. 5 is a fragmentary sectional view taken substantially on the line 55 of FIG. 3 looking in the direction of the arrows.

FIG. 6 is a fragmentary sectional view taken substantially on the line 66 of FIG. 3 looking in the direction of the arrows.

FIG. 7 is an end elevation of the control unit illustrated in FIG. 3.

DETAILED DESCRIPTION OF THE DRAWINGS Referring now more particularly to FIG. 1 an automotive air conditioning system includes a compressor 10 connected through a high pressure line 12, to a port 14 of a control unit 16. The outlet port 18 of the control unit 16 is connected through a conduit 20 with the inlet side 22 of a condenser 24. The outlet side 26 of the condenser 24 is connected through a conduit 28 with a check valve body 30 carried by the receiver dryer tank 32. The tank 32 is connected through a conduit 34 with a combination expansion and system holding unit 36. The unit 36 is connected through a wire 38 to a master control switch on the instrument panel of the vehicle. The unit 36 is connected through a conduit 40 to the inlet side 42 of an evaporator 44. The outlet side 46 of the evaporator 44 is connected through a conduit 48 with the inlet port 50 of the control unit 16. The outlet port 52 of the control unit 16 is connected through the conduit 54 to the low pressure side 56 of the compressor 10. The upper end of the receiver dryer has a connection 58 with a conduit 60 connected with the port 62 of the control unit 16.

Referring to FIG. 4, a wire 64 from the vehicle control panel is connected through an icing switch 66 with a wire 68, connected to the input terminal 70 of the field coil 72, FIG. 3 of the control unit 16, connected through the terminal 74 which in turn is connected to a contact point terminal 76 through a bridging wire 78.

Cooperating contact points 80 and a point carrier 82 which is a press fit in a secondary piston 84 insure good electrical grounding Contact between the piston 84 and the main body cover 86, a spring 88 being provided to Conduct electrical current between the secondary piston 84 and Cover 86 secured to the main body 87 of the Control unit 16.

A spring 90 interposed between the main body Cover 86 and the armature 92 slidably mounted in a cylinder 94 in the main body casting 16, and carrying a valve shaft assembly 96 having an end 98 journaled in a cylinder 100 formed in a bulkhead 102 in an enlarged cylinder 104, and held in place by a snap-ring 106 and sealed against leakage by an O-ring 108.

The valve mechanism carried by the valve shaft assembly 96 is made in two pieces to form an O-ring pocket, the two pieces being secured together to facilitate manufacture, as by a copper brazing operation. An O-ring 110 is trapped in the groove formed between an enlarged portion 111 of the shaft 96 and a piece 112. When the field coil is deenergized by the separation of the point carrier 82 and the piston 84, the spring 90 unseats the valve and O-ring assembly 110, 111 and 112 whereupon the refrigerant fluid by-passes through the port 114 into the chamber 116 and out the port 52 as shown in FIG. 5.

Port 62 connected with the conduit 60 from the receiver dryer tank 32 communicates through a reduced orifice 118 with a cylindrical bore 120. The outer end of the cylindrical bore 120 is closed by a combination bulkhead and stop 122, and is retained in place by a snap ring 124, and is sealed against leakage by an O- ring 126. A reduced diameter portion 127 of the bulkhead 122 provides a stop for a primary piston 128. The primary piston 128 is larger in diameter than is the secondary piston 84. The primary and secondary pistons 128 and 84 are slidably mounted in two diameter cylinders, a shoulder 140 being provided to form two bores 142 and 144 and to limit the movement of the primary piston 128 to the left as viewed in FIG. 3. The reduced diameter portions 85 and 129 of the pistons 84 and 128 provide stops to limit movement of the secondary piston 84 to the right as viewed in FIG. 3. A master control spring 130 is slidably mounted over reduced diameter portions 85 and 129 of the primary and secondary pistons 128 and 84 respectively. The spaces between the primary and secondary pistons 128 and 84 and their respective cylinders are sealed by O-rings 132 and 134 respectively. The spring 130 maintains the point carrier in Contact with the contact points 80, and maintains the primary piston against the stop 127.

Attention is directed to the fact that the terminals 70, 74 and 76 are provided with insulators preferably in the form of cylindrical sleeves 136 and washers 138 which also act as seals.

A oneway check valve assembly 150, FIG. 6, is in the outlet port 18 communicating through the conduit 20 with the condenser 24. The check valve assembly consists of an enlarged diameter bore portion 152 having a valve seat 154 which receives a resilient seat 156 yieldingly urged into sealing engagement with the seat 154 by a spring 158 received in the annular groove 160, and adapter fitting 162 threaded into the bore 152 and sealed by an O-ring 164 to receive the conduit 20 communicating with the condenser 24. A similar type of check valve is employed in the housing 30 of the receiver dryer.

OPERATION Referring now to FIG. 1 the operation of my improved Cycling Control Unit is as follows. When the automotive vehicle is operating the compressor is driven to deliver compressed gas through the conduit 12 to the inlet port 14 and the enlarged cylinder 104 of the control unit 16. The valve assembly formed by the elements 96, 110, 111 and 112 are maintained in the closed position by the solenoid assembly 70, 72, 92, 94 and 96. Compressed gaseous refrigerant from the enlarged cylinder 104 is directed through the check valve assembly 150 to the outlet port 18 communicating with the conduit 20 to the condenser 24. The construction of the check valve is such that a lesser area of the valve is subjected to the pressure in the enlarged cylinder 104 than is subjected to the pressure on the opposite side of the check valve assembly 150. This results in a pressure drop in the system.

In the condenser 24, heat is extracted from the compressed gaseous refrigerant and it is converted to a liquid state. The liquid refrigerant flows through the outlet 26 under pressure from the conduit 20 and flows through the conduit 28 to the check valve 30 in the receiver dryer tank 32. A pressure drop is encountered in the check valve assembly 30 similar to that described in the check valve assembly 150 between the control unit 16 and the condenser 24. Liquid refrigerant in the receiver dryer 32 is transmitted through the conduit 34 to the combination expansion and system holding unit 36. It will be noted that from the expansion and holding unit 36 liquid refrigerant is transmitted through the conduit unit 40 at a reduced pressure to the evaporator 44 where the refrigerant boils off, picks up heat returning to a vapor state. This is where the cooling effect in the automotive vehicle is achieved by the extraction of heat from the air in the vehicle from the blower circuit wherein the liquid refrigerant absorbs heat from the air through the fins to convert the liquid refrigerant back to the vapor state. The liquid refrigerant thus boils off and is returned to a vapor state, picking up heat and cooling the vehicle and it then flows through the outlet 46 to the conduit 48 back to the inlet port 50 of the control unit 16.

Reverting back now to the receiver dryer 32 attention is directed to the fact that the refrigerant in the upper portion of the receiver dryer is in a gaseous state rather than a liquid. This pressure is exerted through the connections 58 and the conduit 60 to the port 62 of the control unit 16. The pressure thus exerted in the port 62 communicates through the reducing orifice 1 18 into the cylindrical bore 120 where it exerts pressure on the right-hand side of the primary piston 128. This force urges the piston 128 toward the left in the bore 144 until the shoulder 146 engages shoulder 140 in the inner end of the bore 144 of the control unit 16, in opposition to the force exerted by the master control spring 130. The force thus exerted by the spring 130 is transmitted through the shoulder 148 to the secondary piston 84. This urges the secondary piston 84 toward the left whereby contact is maintained through the cooperating contact points 80. Attention is directed to the fact that the grounding spring 88 interposed between the secondary piston 84 and the cover 86 and the bore 87 maintain good electrical contact. The compressor l0 continues to operate exerting increased pressure through the internal line 166 communicating through the longitudinal passage 168 extending along the control unit 16 to the cross bore 170 in the control unit 16 communicating with the bore 142 on the lefthand end of the secondary piston 84. The outer end of the bore 166 is closed by a plug 172. When the pressure increases to a previously determined pressure the piston 84 is moved to the right in opposition to the force exerted by the spring 130. The cooperating contact points are then separated whereupon the solenoid assembly formed by the elements 70, 72, 92 and 96 is urged toward the right by the spring thereby opening the valve assembly 110, 111 and 112. The system then by-passes through port 114, chamber 116, outlet port and adapter 52 into the conduit 54 then back to the low-pressure side of the compressor 10.

I claim:

1. An air conditioning system for an automotive vehicle having a master control switch on the instrument panel and including a compressor cycling unit, said system comprising;

A. a compressor having,

1. a high pressure side, and

2. a low pressure suction side;

B. a condenser to receive a compressed gaseous refrigerant from said high pressure side and to convert same into a liquid state;

C. a receiver-dryer to receive the liquid refrigerant,

said refrigerant in the upper portion thereof remaining in a gaseous state;

D. a combination expansion and system holding unit to receive the liquid refrigerant from said receiverdryer;

E. an evaporator to receive said liquid refrigerant at a reduced pressure where it boils off, picks up heat, returning to a vapor state;

F. a compressor cycling control unit including,

1. a first inlet port from said high pressure side,

2. a first outlet port connecting with said condenser,

3. a second inlet port from said evaporator,

4. a second outlet port connecting with said low pressure side,

5. a valve means normally in a closed relation between an enlarged cylinder communicating with said first inlet port and first outlet port, and a chamber communicating with said second inlet port and second outlet port;

G. means to control said valve means comprising,

i. a longitudinal bore in said cycling control unit providing a first, enlarged portion and a second, reduced diameter portion;

2. a primary piston slidably engaged in said enlarged portion, normally seated against a stop means to define a bore chamber therebetween;

3. a secondary piston, spaced from said primary piston, slidably engaged in said reduced diameter portion;

4. a compression spring between said pistons to normally, forcibly maintain said spacing;

5. said electric circuit connecting between the control switch and an input terminal of said solenoid and from an output terminal thereof to ground contacts to said secondary piston to the housing of said cycling control;

6. a third inlet port from said receiver-dryer upper section to said bore chamber, the pressure exerted on the gaseous refrigerant moving said primary piston against a shoulder stop defined by the juncture of said enlarged and reduced diameter bore portions;

7. by-pass conduit means connecting between said third inlet port and said secondary piston in a manner whereby pressure beyond said predetermined value moves said secondary piston towards said primary piston in opposition to the forces of said compression spring, opening said ground contacts, deenergizing said solenoid, opening said valve assembly to by-pass the refrigerant from said first inlet port through said second outlet port back to said low pressure side.

2. The device as defined in claim 1 wherein said valve means comprises a solenoid-controlled valve, including a compression spring to open said valve when an electric circuit thereto from the control switch is broken.

3. The device as defined in claim 1 including a first check valve means in said first outlet port to reduce the pressure in the system.

4. The device as defined in claim 1 wherein the construction of said first check valve is such that a lesser area of the valve is subjected to the compressor pressure in said enlarged cylinder side than is subjected to the pressure on the opposite side thereof to accomplish said pressure reduction.

5. The device as defined in claim 4 wherein said means to reduce the pressure as said liquid refrigerant enters said receiver-dryer comprises a second similar check valve. 

1. An air conditioning system for an automotive vehicle having a master control switch on the instrument panel and including a compressor cycling unit, said system comprising; A. a compressor having,
 1. a high pressure side, and
 2. a low pressure suction side; B. a condenser to receive a compressed gaseous refrigerant from said high pressure side and to convert same into a liquid state; C. a receiver-dryer to receive the liquid refrigerant, said refrigerant in the upper portion thereof remaining in a gaseous state; D. a combination expansion and system holding unit to receive the liquid refrigerant from said receiver-dryer; E. an evaporator to receive said liquid refrigerant at a reduced pressure where it boils off, picks up heat, returning to a vapor state; F. a compressor cycling control unit including,
 1. a first inlet port from said high pressure side,
 2. a first outlet port connecting with said condenser,
 3. a second inlet port from said evaporator,
 4. a second outlet port connecting with said low pressure side,
 5. a valve means normally in a closed relation between an enlarged cylinder communicating with said first inlet port and first outlet port, and a chamber communicating with said second inlet port and second outlet port; G. means to control said valve means comprising,
 1. a longitudinal bore in said cycling control unit providing a first, enlarged portion and a second, reduced diameter portion;
 2. a primary piston slidably engaged in said enlarged portion, normally seated against a stop means to define a bore chamber therebetween;
 3. a secondary piston, spaced from said primary piston, slidably engaged in said reduced diameter portion;
 4. a compression spring between said pistons to normally, forcibly maintain said spacing;
 5. said electric circuit connecting between the control switch and an input terminal of said solenoid and from an output terminal thereof to ground contacts to said secondary piston to the housing of said cycling control;
 6. a third inlet port from said receiver-dryer upper section to said bore chamber, the pressure exerted on the gaseous refrigerant moving said primary piston against a shoulder stop defined by the juncture of said enlarged and reduced diameter bore portions;
 7. by-pass conduit means connecting between said third inlet port and said secondary piston in a manner whereby pressure beyond said predetermined value moves said secondary piston towards said primary piston in opposition to the forces of said compression spring, opening said ground contacts, deenergizing said solenoid, opening said valve assembly to bypass the refrigerant from said first inlet port through said second outlet port back to said low pressure side.
 2. The device as defined in claim 1 wherein said valve means comprises a solenoid-controlled valve, including a compression spring to open said valve when an electric circuit thereto from the control switch is broken.
 2. a low pressure suction side; B. a condenser to receive a compressed gaseous refrigerant from said high pressure side and to convert same into a liquid state; C. a receiver-dryer to receive the liquid refrigerant, said refrigerant in the upper portion thereof remaining in a gaseous state; D. a combination expansion and system holding unit to receive the liquid refrigerant from said receiver-dryer; E. an evaporator to receive said liquid refrigerant at a reduced pressure where it boils off, picks up heat, returning to a vapor state; F. a compressor cycling control unit including,
 2. a first outlet port connecting with said condenser,
 2. a primary piston slidably engaged in said enlarged portion, normally seated against a stop means to define a bore chamber therebetween;
 3. a secondary piston, spaced from said primary piston, slidably engaged in said reduced diameter portion;
 3. a second inlet port from said evaporator,
 3. The device as defined in claim 1 including a first check valve means in said first outlet port to reduce the pressure in the system.
 4. The device as defined in claim 1 wherein the construction of said first check valve is such that a lesser area of the valve is subjected to the compressor pressure in said enlarged cylinder side than is subjected to the pressure on the opposite side thereof to accomplish said pressure reduction.
 4. a second outlet port connecting with said low pressure side,
 4. a compression spring between said pistons to normally, forcibly maintain said spacing;
 5. said electric circuit connecting between the control switch and an input terminal of said solenoid and from an output terminal thereof to ground contacts to said secondary piston to the housing of said cycling control;
 5. a valve means normally in a closed relation between an enlarged cylinder communicating with said first inlet port and first outlet port, and a chamber communicating with said second inlet port and second outlet port; G. means to control said valve means comprising,
 5. The device as defined in claim 4 wherein said means to reduce the pressure as said liquid refrigerant enters said receiver-dryer comprises a second similar check valve.
 6. a third inlet port from said receiver-dryer upper section to said bore chamber, the pressure exerted on the gaseous refrigerant moving said primary piston against a shoulder stop defined by the juncture of said enlarged and reduced diameter bore portions;
 7. by-pass conduit means connecting between said third inlet port and said secondary piston in a manner whereby pressure beyond said predetermined value moves said secondary piston towards said primary piston in opposition to the forces of said compression spring, opening said ground contacts, deenergizing said solenoid, opening said valve assembly to by-pass the refrigerant from said first inlet port through said second outlet port back to said low pressure side. 